feat(targetNamespace): Add field to edit target namespace.

- add new tab "document" on properties panel, because target namespace is
  part of definitions and definitions tab is not the best position
- it is possible to edit "target namespace" of the diagram on the
  definitions tab

related to #CAM-1235
Merge branch 'master' of github.com:camunda/camunda-modeler
feat(morph/activities/gtw): Morph bpmn elements

- it is possible to morph a created bpmn element into another bpmn element
- for example it is possible to morph a service task into a user task etc.

related to CAM-303
Merge branch 'master' of github.com:camunda/camunda-modeler
fix(property-panel/help): adjust help text to latest docs
fix(diagram/boundary-event): fix flow attachment

Sequence flows and associations attach to boundary events properly.

- a boundary event is an event (in the diagram sense) now

Closes CAM-232
Merge branch 'master' of github.com:camunda/camunda-modeler
chore(cleanup): remove commented out text

Related to CAM-1235
chore(kepler): Import project to Eclipse Kepler

- update the version of graphiti from 0.9.x to 0.10.0 in MANIFEST.MF
- use the new infrastructure of graphiti, ie. use the new DiagramBehavior
  etc.

related to CAM-887
Merge branch 'kepler' of github.com:camunda/camunda-modeler into kepler